Earlier quoted context omitted.
The pitch variants are also highly regional but that’s an interesting idea. I wouldn’t want to give it to learners in use cases I can think of, when correct data is available though (just with licensing headaches/costs) The correct data already exists, so I'm not sure what the point is besides having a less accurate but freer option
99% (or more) of the recordings you might find for training would be in the standard accent unless you were specifically digging for regional accents.
it's also changing generationally